a.Consider testing H0: m=80. Under what conditions should you use the t-distribution to conduct the test?

b.In what ways are the distributions of the z-statistic and t-test statistic alike? How do they differ?

Short Answer

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a.Two conditions to conduct the test for t-distribution

b. Shapes are alike, but distribution and deviation are different

Step by step solution

01

Conditions to use the t-distribution to conduct the test

a)

Two requirements have got to be met before the t-distribution is employed. The first is the sampling distribution's normality. Such that the x-bar uses a traditional distribution. It may accomplish in one of two ways. It would be best to grasp that the individual observations follow a standard distribution, or like to own a large sample size (more than 30), so it can depend upon the central limit theorem. Now, the t-distribution after estimating the population variance with the sample variance.

02

Shapes, distribution, deviation

b)

The distributions are smooth in shape, and the t and z distributions are symmetric. Each of them has a zero mean. Both are continuous, bell-shaped distributions with denser tails than the z-distribution.

The t-statistic employs the sample standard deviation, whereas the z-statistic employs the standard deviation. The exact form of t-distribution changes as df increases. As df increases, the t distribution forms a normal z-score distribution. The t-distribution is flatter and more extensive, while the standard z-distribution has a more prominent central peak.

The zdeviation indicateshow fara fact set is from the suggested or specific facts set in trendy deviations. A z-test compares a pattern to a described populace and is typically used to resolve troubles related to large samples (n > 30). Z-testalso canbebeneficial while checking out a hypothesis. They are usually maximum beneficial while the same olddeviation is known.

T-tests, like z-tests, are calculations used to test a hypothesis. Still, they are most helpfulindetermining whether there is a statistically significant difference between twogroups ofindependentsamples. In other words, a t-test determines whether a difference in the means of two groups is likely to have occurred bychance.

T-tests are generally used when dealing with problems with a small sample size (n = 30).

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Most popular questions from this chapter

What is the difference between Type I and Type II errors in hypothesis testing? How do α and β relate to Type I and Type II errors?

Authorizing computer users with palm prints. Access to computers, email, and Facebook accounts is achieved via a password—a collection of symbols (usually letters and numbers) selected by the user. One problem with passwords is that persistent hackers can create programs that enter millions of combinations of symbols into a target system until the correct password is found. An article in IEEE Pervasive Computing (October-December 2007) investigated the effectiveness of using palm prints to identify authorized users. For example, a system developed by Palmguard, Inc. tests the hypothesis

\({H_0}\): The proposed user is authorized

\({H_a}\): The proposed user is unauthorized

by checking characteristics of the proposed user’s palm print against those stored in the authorized users’ data bank.

a. Define a Type I error and Type II error for this test. Which is the more serious error? Why?

Consider the test \({H_0}:\mu = 70\) versus \({H_a}:\mu \ne 70\) using a large sample of size n = 400. Assume\(\sigma = 20\).

a. Describe the sampling distribution of\(\bar x\).

b. Find the value of the test statistic if\(\bar x = 72.5\).

c. Refer to part b. Find the p-value of the test.

d. Find the rejection region of the test for\(\alpha = 0.01\).

e. Refer to parts c and d. Use the p-value approach to

make the appropriate conclusion.

f. Repeat part e, but use the rejection region approach.

g. Do the conclusions, parts e and f, agree?

An analyst tested the null hypothesis that μ 20against the alternative hypothesis that μ <20. The analyst reported a p-value of .06. What is the smallest value ofαfor which the null hypothesis would be rejected?

A random sample of 175 measurements possessed a mean x¯=8.2 and a standard deviation s = .79.

a. Test H0:μ=8.3 against Ha:μ8.3Use a=0.05

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